Cesium Atomic Fountain Clock Ntsc - 01 Optical System

Cs atomic fountain clock is the reappearance of "seconds" definition of time and frequency standard device, has the highest accuracy, as a reference clock calibration with other atomic clock, is a time and frequency system based. Cs atomic fountain clock consists of the optical system, the physical system, circuit system and control system, in order to pulse mode.Cs atomic fountain clock optical system provides cesium atomic manipulation and transition probabilities for the detection of all laser, is the realization of Cs cold atomic samples, forming atomic fountain and two-level detection is the key, its performance directly affects Cs atomic fountain clock operation of the machine, the development of the Cs atomic fountain clock machine operation requirements the optical system for the Cs atomic fountain clock is the basis and key.The paper is based on the NTSC-01Cs fountain clock optical system as main content, which includes two aspects:1,NTSC-01fountain clock optical system. Optical system provide with Cs atom manipulation and transition probabilities for the detection of all laser. The research content mainly includes:(1),Laser frequency control:includes laser frequency stability and AOM on the optical frequency control. The saturated absorption frequency stabilization, frequency stability up to3X10-12/s Using AOM to two-dimensional magetic-optical trap pre-cooling laser and three-dimensional magneto-optical trap capture laser corresponding to the frequency detuning and fast frequency shift, so as to capture and rapid manipulation of atoms according to time series up and detection control system.(2),Laser power amplification and control:includes cooling and trapping laser amplification and AOM to capture laser power control. Laser power of Two-dimensional magneto-optical trap produce through injection into the traveling wave amplifier, and that of Three-dimensional magneto-optical trap generated by injected locking into two high power slave laser diode. Exponential decay of six capturing beam power makes atoms further cooling according to Sub-Doppler cooling mechanism when atom are launched under timing control. (3),Laser transmission:includes laser power and polarization and polarization maintaining fiber couping. Using telescope system for coupling power and quarter wave plate and extinction ratio measurement for coupling polarization between laser and polarization maintaining fiber.(4),Laser beam parameter optimization:it completed by adjusting laser expanded and collimation system, and make it meet cooling and capturing Cs atoms in laser collimation, direction, power, polarization state requirements.By measuring the capture atom number is2x10and intensity of time of flight at launching by81cm satisfy NTSC-01fountain clock follow-up requirements, It indicates that optical system can serve NTST-01successfully.2,Frequency tuning of external-cavity diode laser with liquid crystal. We report a frequency tunable external-cavity DFB laser using a liquid crystal variable retarder(LCVR) based on low tunable voltage and no hysterisis and mechanical moment. The laser frequency can span7GHz when bias voltage varies1.6V, covering all the saturated absorption spectroscopy of the Cs D2line. The external cavity of diode laser with a cat-eye reflector enhances stabitily of DFB laser. It is a better choice as an alternative to traditional cooling laser source.